Multiple Z4 Questions

Hi there
I'm about to build a Zen4 amp, and want to build it balanced.
below I have summed up several questions i have about this construction:

1. I understand that the transformer needs to twice the size of that of en singlended Zen4 - I have an 2x25 volt / 29 amp in stock - this would give me 70 volts - would that be a problem - I know that the output would med less, but will it work - and how about BIAS / idle current ???

2. Capacitors that will handle +70 volts seem to be rare, if not really expensive in my part of the world - could I use 2x 50 volts caps i seriel, thus giving me half the capacitance, but twice the voltage handling ???

3. I'm thinking of building a diodebridge using 150v / 8 amp Fast recovery diodes - would those die during the start up current drawed by the PSU ?? - should I instead go for en traditional heavy duty diodebridge ???

4. connections - would someone summon up those - now I know that my negative signal goes to the posiotive on one of the chanals, and the positive goes to the other chanal, and the output is taken over the two chanals positive output - but how do I connect the ground of the two chanals - together and the linked to chassis / common ground ?

How do I connect the two chanals to the PSU ??

Hope someone has the time and patience to help a newbie like me - thnx in advance !!!

Hans Houmøller

Nelson Pass

The one and only
Paid Member
2001-03-29 12:38 am
If you want to use that transformer, I would recommend
an inductor in series with the primary to take down the
voltage until you have the 50 volts, as 70 volts is getting
to be too much for the circuit as published. If you have
a Variac, you can experiment with different values of inductor
while operating the circuit until you get the right one.